Study On Safety Risk Assessment Of Open Cut Metrostation Project

With the rapid development of China's national economy and urbanization,the metro has become the best choice to solve the urban traffic problems.The open-cut method is one of the most common construction method in subway station foundation pit construction,in order to ensure the smooth development of subway station construction,avoid the occurrence of safety accidents,it is imminent to study safety risk assessment method of open-cut subway station project systematically.In this paper,firstly,the WBS-RBS method is used to identify the risk factors and events in the construction of the subway station,and the general risk assessment index system is established.Secondly,the overall risk assessment method is established based on index system.Then,a special and general risk assessment method is established based on fuzzy interval.Finally,it is applied to engineering examples.The main research results are as follows:(1)Combined with the characteristics of subway station engineering,the paper expounds the theoretical background of risk assessment of subway station engineering.Firstly,the basic concept,characteristics and classification of the deep foundation pit of subway station are discussed;Secondly,this paper introduces the content and process of risk management of deep foundation pit of subway station;In the end,the author analyzes the cause of the accident and the responsibility unit of the subway station foundation pit,and defines the research object of this paper is the construction risk assessment of the open-cut subway station project.(2)Firstly,combined with the construction characteristics of the open-cut method,the WBS method is used to divide the working structure of the open-cut pit construction into 8 parts,the RBS method is used to decompose the risk from the perspective of 4M1 E.Then,WBS-RBS coupling matrix is formed,which is used to identify the risk events and risk factors comprehensively and systematically.Finally,a general index system of safety risk assessment for construction of open-cut metro station is established.(3)The risk factors of the overall risk assessment of the open-cut subway station project are determined by the way of risk transfer path.The paper establishs the overall risk assessment index system and the risk grade determination standard of the open-cut subway station project.(4)Special and general risk assessment method based on fuzzy interval.In combination with the actual situation of the research project,the author modifys the “expert others belief index” quota of Dr.Li Junsong.The relative weights of the index are determined.Using the “expert others belief index” evaluation standard to determine the weight of experts.And the improved AHP is used to get the weight of each risk index.Then the probability and the loss of the risk factors or events and the confidence level are obtained by using the expert investigation method.By using the fuzzy theory,the distribution function of the normal distribution is chosen as the membership function.SO the fuzzy interval of risk degree is obtained,and the risk grade is determined according to the risk grade standard.(5)Engineering application.The risk assessment model established in this paper is applied in Fuzhou Metro station.The conclusions of the assessment are in good agreement with the actual situation of the project.The results show that the risk assessment index system of open-cut subway station project and risk assessment method have good adaptability and effectiveness.